We’ve known for years about the health benefits of omega-3 fatty acids found in fish like salmon, sardines and herring, as well as in flax and walnuts. Eating omega-3s regularly has been shown to reduce the risk of cardiovascular disease, prolong survival in those with heart disease, improve joint health and reduce serum triglyceride levels.

Now we have another reason to like omega-3s: They may prolong life, according to a study by the University of California, San Francisco. The mechanism appears to be the preservation of the length of certain snippets of DNA known as telomeres.

Ready for a science lesson? Telomeres sit at both ends of our 46 chromosomes. They keep the chromosome’s DNA nice and tidy by preventing it from looping on itself or binding with other DNA strands. Each time a cell divides, the DNA coil unwinds all but the telomeres, allowing the DNA to be copied. After cell division, the DNA rewinds but the telomere shortens ever so slightly.

After repeated cell divisions, the telomere may become too short and the DNA can be damaged. As a result, the cell soon stops dividing altogether after about 50 cell divisions – the cellular equivalent of aging. And without new cell production, organ systems can age more rapidly. So the search is on for compounds that can preserve telomere length with the hope that longer telomeres means longer life.

In the UC San Francisco study, researchers measured telomere length over five years in 608 patients who had known cardiovascular disease and heart attacks. The results: Those with high levels of omega-3s in their blood had significantly less shortening of telomeres over five years compared to those with lower levels.

The study, published in the Journal of the American Medical Association, focused only on omega-3 fatty acids from fish (DHA and EPA) and not the type found in plant seeds and their processed oils, like canola or soybean. It was unknown if the sources of DHA and EPA in the study were from prepared fish or from supplements. Regardless, previous studies support the health benefits of fish-derived omega-3s, but high-quality fish oil supplements should offer similar benefits.

Other studies have shown that short telomere length correlates with heart failure, heart attacks and death. What remains unclear is whether the shortening of telomeres is a cause of these heart problems or simply a marker for another underlying process leading to cellular aging. Stay tuned.